A negative impedance circuit is a device whose current is inversely proportional to the voltage across it. A negative impedance circuit can only be achieved with active circuitry.
Existing techniques for developing a negative impedance typically involve operational amplifier (op-amp) circuits having a “deboo” type structure that direct feedback current to a non-inverting terminal of the op-amp. These negative impedance circuits, however, may have limited operating ranges. This is caused by a requirement that the op-amps have a gain greater than unity in order to develop the negative impedance. Thus, if the voltage at the non-inverting terminal of the op-amp should approach the supply rails for the op-amp, the op-amp will saturate and the negative impedance circuit will become a positive resistance. The op-amp will cease generating a gain and the negative impedance circuit will merely become a positive resistance load.
Accordingly, there is a need in the art to provide techniques to develop a negative impedance circuit that operates to its supply rails.